The characteristics of physical facilities for housing animals have not changed substantially in the last 10 years. Room sizes, corridor systems, cage and rack systems, finishes, and physical labor have changed little. The ability to genetically alter mice has led to exponential population growth and changes in the physical environment for their care. The impetus for the change is the value of these genetically altered animals, rising operational and per diem costs, and the difficulty in attracting and retaining highly qualified animal care staff. Four of the top 10 medical schools (in terms of grant money) have mouse populations exceeding 25,000 cages and have become mouse research and breeding facilities and yet contain no automation.

With proper facility design, cost-effective care of large mouse colonies and attendant sanitation of cages and racks can be achieved. At the new 55,000-cage mouse facility of Baylor College of Medicine in Houston, Texas, the FY 2000 per diem rate of $0.31/cage (without a filter top) is projected to be reduced when the new $40 million facility is occupied by the middle of 2000. The initial investment is to be recovered from per diem charges. (Note that all prices are in year 2000 dollar amounts and are given for illustrative purposes only; actual prices can vary.) Proper facility design, although requiring a large capital investment, should reduce per diem costs. Many of the lessons learned from designing animal facilities to house 20,000 or more mouse cages cost-effectively can be adapted to smaller facilities. The Baylor College of Medicine project is referenced many times in this section because of the emphasis spent on

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4
Integration of Design, Equipment, Operation, and Staffing: A Contemporary Case Study
The characteristics of physical facilities for housing animals have not changed substantially in the last 10 years. Room sizes, corridor systems, cage and rack systems, finishes, and physical labor have changed little. The ability to genetically alter mice has led to exponential population growth and changes in the physical environment for their care. The impetus for the change is the value of these genetically altered animals, rising operational and per diem costs, and the difficulty in attracting and retaining highly qualified animal care staff. Four of the top 10 medical schools (in terms of grant money) have mouse populations exceeding 25,000 cages and have become mouse research and breeding facilities and yet contain no automation.
With proper facility design, cost-effective care of large mouse colonies and attendant sanitation of cages and racks can be achieved. At the new 55,000-cage mouse facility of Baylor College of Medicine in Houston, Texas, the FY 2000 per diem rate of $0.31/cage (without a filter top) is projected to be reduced when the new $40 million facility is occupied by the middle of 2000. The initial investment is to be recovered from per diem charges. (Note that all prices are in year 2000 dollar amounts and are given for illustrative purposes only; actual prices can vary.) Proper facility design, although requiring a large capital investment, should reduce per diem costs. Many of the lessons learned from designing animal facilities to house 20,000 or more mouse cages cost-effectively can be adapted to smaller facilities. The Baylor College of Medicine project is referenced many times in this section because of the emphasis spent on

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reducing costs through life-cycle cost analysis, innovation, and adaptation. It should be noted that many of the projected costs and cost savings are estimates made during the design phase. Actual results will be known several years after this project is completed. The detailed analysis is presented here to highlight the necessity for a comprehensive planning process and the need to define goals and set targets. The design team should include the facility director, facility manager, researchers, and representatives of the animal care staff who bring day-to-day front-line experience.
With direct labor representing 50-65% of operating costs, investment in technology that reduces staff or makes current staff more efficient is critical. The committee's recommendations are organized around physical and operational issues.
VENTILATED RACKS
Many institutions have used ventilated microisolator cage and rack systems to extend cage-changing intervals from twice a week to once a week or once every 2 weeks. This extension of the cage-changing interval could allow a doubling of the mouse-cage census without substantially increasing the number of staff involved. Lengthening cage-changing intervals also decreases the load for the cage-wash centers because each cage is washed less frequently. (However, since laboratory animal care technicians also clean rooms, take censuses, receive animals, and support area management, material transport, training, and meetings in addition to cage changing, it should not be expected that halving the cage-changing frequency will lead to a doubling of productivity.) The capital investment in ventilated micro-barrier cages and racks is substantially larger than in static microbarrier housing systems. For example, a 126-cage ventilated rack with water bottles costs 139% more than a double-sided static rack, and a ventilated rack with automatic watering costs 230% more. However, site-by-site comparison of these cage and rack systems, considering total operational costs (equipment, sanitation, personnel, and space), typically indicates, on the basis of committee experience, a payback period of under 5 years for the higher initial investment. Payback periods will vary considerably, depending on the current and projected cage-rack systems, cage-changing frequencies, use of water bottles or automatic watering, mechanical HVAC capacity, room size and configuration, and volume equipment discounts. For some large operations, the payback period is not an important consideration, because hiring and retaining sufficient staff are difficult during a tight labor market. Unless an institution plans to extend the cage-changing frequency substantially (for example, from once a week to once every 2 weeks) or increase the

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density of cages per rack (from 84/rack to 126/rack or 140/rack, for a 50% or 67% increase), using ventilated racks might not be warranted. Besides the high initial cost of ventilated racks, drawbacks include poor visibility into the cage, the ergonomic stress involved in viewing the bottom and top shelf, and rack weight. Recent modifications, such as rear-mounted feeders and shelf-free rack designs, have improved cage visibility. Ergonomic access can be addressed by assuming 80% and 90% rack use with 140-cage (top and bottom shelf) and 126-cage (bottom shelves) ventilated racks, respectively. With such rack use, the bottom or top row of cages (or both) can be used to temporarily accommodate extra caging or expansion without an increase in floor space. Ventilated racks are heavy—typically 1,000 lb or more when fully loaded. Designing a room where only minimal rack movement is required or increasing the caster diameter from a standard 5 in. to 8 in. can assist with the weight issue. In planning new facilities with ventilated racks and 2-week cage-changing intervals, it should be assumed that 10-20% of the cages will be changed once a week to accommodate special mice strains, such as mice with naturally occurring or experimentally induced diabetes.
VENTILATED-RACK SUPPLY AND EXHAUST
Ventilated racks can be configured with integral HEPA supply and exhaust blowers or connected to a building supply and exhaust. Ventilated racks that do not capture exhaust are not recommended, because heat, allergens, and odors can be returned into the room unless the exhaust is HEPA-filtered. Institutions using large ventilated racks can profit from direct connection to a building HEPA supply and be nonfiltered (or filtered, depending on location and application) because of cost savings, ventilation redundancy, and lower maintenance costs. At Baylor College of Medicine's new facility, the decision to build a HEPA-filtered building supply system instead of using individual rack systems saved over $16,000/room (supply and exhaust HEPA blowers would cost $2,500/ rack, and each room has nine racks, for a cost of $22,500/room; but building supply, exhaust, and ductwork cost only $6,500/room). With individual rack systems, if the blower fails, ventilation rates revert to a static state. Using building systems with redundant supply and exhaust units on emergency power allows uninterrupted ventilation to each rack. For more information on ventilated racks, see Lipman (1993).
AUTOMATIC WATERING
A 16-oz water bottle in a microisolator with four to five mice in it will not be sufficient for 2 weeks. Extending cage-changing frequencies to

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once every 2 weeks requires automatic watering, weekly changing of the water bottle, or a larger water bottle (28-30 oz). Many institutions using ventilated racks with a 2-week cage-changing frequency use automatic watering. Early automatic watering systems with the valve attached to the cage were prone to leaks or mouse dehydration because of improper docking of the valve. On the basis of committee experience, recent automatic watering systems with the valve attached to the cage, if docked appropriately, perform as well as water bottles. Replacing cages on the rack requires priming of the valve by cage-changing personnel and researchers. Automatic watering systems with the valve attached to the rack do not require priming but should be wiped with a disinfectant before cage replacement to prevent cross contamination. Changing standard 16-oz water bottles weekly and cages every 2 weeks might be practical, especially where the water bottle is outside the cage. At Baylor College of Medicine, investigators' rejection of automatic watering necessitated redesign of the low-profile microisolator top to accommodate a 28-oz water bottle and a 2-week cage-changing frequency. Baylor conducted clinical trials by acidifying the water to a pH of 2.3 and confirmed that the 28-oz water bottle did not exhibit bacterial or fungal growth in 14 days (Robert Faith, personal communication). Water bottles pose serious labor and ergonomic issues for an animal facility. Uncapping, washing, filling, recapping, and sterilization are time consuming and labor intensive and can lead to repetitive-motion injury.
UNIVERSAL ROOM DESIGN
An animal housing and research room (AHRR) size of 16 × 22 ft can accommodate a wide variety of racks, pens, and species. Mouse AHRRs with an average of two mouse cages per assignable square foot (ASF) are considered to have high density (Table 3).
At Baylor College of Medicine, researchers rejected the typical six double-sided mouse racks arranged library-style because only 3 feet was left between the faces of racks, necessitating movement of the 1,200-lb
TABLE 3 Number of Cages per Square Foot by Percent Rack Usea
Fraction of Racks Used, %
Total No. Cages
No. Cages per Square Foot
80
672
1.91
90
756
2.15
100
840
2.39
a Assuming 16 × 22-ft or 352-ft2, room with six 140-cage racks.

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ventilated racks during cage-changing and procedures on the animals. Breeding rates in some mouse strains were reduced when racks were moved (Robert Faith, personal communication). In response to those issues, the room was configured with three single-sided racks against each 22-ft wall and three double-sided racks down the middle. The six single-sided racks and three double-sided racks yielded the equivalent of six double-sided racks with 5-ft between the faces of racks. If the 5-ft aisle is used as procedure space and cage-changing space, the ventilated racks are only moved two to four times per year for washing. During cagechanging, an animal transfer station is moved down the 5-ft aisle, bringing the transfer station to the cage, in contrast with what happens with the library style configuration, in which cages are brought to the transfer station. Single-sided ventilated racks cost 75% as much as double-sided racks, and the drawback to this design is higher equipment costs. In the Baylor College of Medicine project, this rack arrangement resulted in an increased cost of equipment of about $18,000/room, or a total increase of about $1 million. This increase was thought justified because it makes the room much more user friendly to research staff and animal husbandry staff. The increased efficiency and reduction of injuries resulting from not requiring movement of heavy racks for cage changing or experimental manipulation of animals will quickly pay back the additional cost. From the 1999 ARS survey, the average for cage-changing per person for group 2 and 3 institutions ranges from roughly 400 cages per week for individually ventilated cages to 800-950 cages per week for other types of caging (see Table 8l n, Appendix C). Most institutions used a change station for microisolator cages and for individually ventilated cages. Baylor College of Medicine expects at least 300 cages/day per person (roughly 1,500/ week) with the revised rack layout and new transfer-station design, resulting in 20-50% increase in productivity per cage changer. Experience will test that expectation and will reveal any ergonomic problems that arise. Room mockups were useful in choosing the final room size and layout.
ANIMAL TRANSFER STATIONS
Transfer stations may be clean-air workstations or biologic safety cabinets with a 10-in. or 12-in. sash opening on one side. The restricted sash opening affects cage-changing frequency and has historically limited cage changes to 200-250 cages/day per person. Some institutions use workstations with two sash openings (front and back. At Baylor College of Medicine, a new four-side open transfer station was developed to take advantage of the 5-ft aisle between racks and to increase cage-changing productivity to 300 cages/day per person. The advantages of the new

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transfer station include an adjustable 18- to 24-in.-high sash, allowing unencumbered hand movement, and a team approach to cage changing. The new four-sided transfer station is a workstation and does not have the biologic-containment properties of a biologic safety cabinet, so only product protection is provided.
ROBOTICS
For 4 years, three animal facilities in Sweden have been successfully operating numerous cage-washing facilities with robots handling the monotonous and repetitive chores of dumping waste from cages, placing cage components (bottom, top, wire bar lid, and bottle) on tunnel washers, removing cage components from tunnel washers, and filling cages with bedding. The principal motivation for using robotics in Sweden is the recognition that the highest percentage of work-related injuries in an animal facility occur in the cage-washing area because of repetitive-motion injuries, sensitization to allergens created during cage-dumping, and heavy lifting. To comply with occupational health and safety rules in Sweden, which require proof that a task associated with health hazards can be performed only by humans, directors of animal research facilities have explored the use of robotics. The cage-washing area typically experiences the highest staff turnover rate. The potential of robotics to decrease costs remains to be determined. At Baylor College of Medicine, robots will process the 55,000 soiled and clean cages per 2 weeks (10 working days) with indexing tunnel washers (a tunnel washer that moves a batch of cages at a time through the various (prewash, wash, rinse, and dry) treatment compartments), conveyors, and a vacuum bedding system. In a presentation to Tradelines, a for-profit seminar group, data provided by Baylor College of Medicine indicated that the $1.2 million premium for using robots, indexing tunnel washers, a vacuum bedding system, and special material-handling equipment resulted in a payback of 4.11 years. The robots have been successfully used in many automated production facilities in the automotive industry for over 20 years with a mean time between failures of 50,000 hours for the entire robot assembly. Robots should be seriously considered for facilities that process 4,000-5,000 cages/ day (four staff at two tunnel washers) and evaluated when cage-processing reaches 2,000-2,500 /day (two staff at one tunnel washer). The cost of cage-processing robots is expected to decrease as more installations come on line and engineering costs are amortized over many projects. With a projected growth of 20-22% per/year in mouse census, robots will allow animal facilities to redirect valuable staff to animal-husbandry functions rather than monotonous and repetitive cage-washing activities.

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VACUUM BEDDING SYSTEM
Handling of soiled and clean bedding in an animal facility is a laborintensive task. Soiled bedding is removed from cages and waste is hauled to a dumpster manually at most animal facilities. Clean bedding can be automatically dispensed at the end of tunnel washers by manually filling hoppers of an automatic bedding dispenser from 40 to 50-lb bedding bags. Vacuum bedding systems can be used manually or in conjunction with robots to pneumatically transport soiled bedding to remote dumpsters and transport clean bedding to bedding dispensers. The vacuum creates a downdraft at the dump station, minimizing environmental dust and allergens. There are two other waste-disposal systems. One grinds up the waste and bedding, adds water, moves the waste by a pipe to a press that squeezes out the water, and puts the waste in a dumpster. A related method is to grind up the waste, add water, and discharge into the sewer. One must check with local authorities to use this method.
EXPANDABLE-CONTRACTIBLE BARRIERS
Most animal facilities are designed with a fixed percentage of barrier space (housing space that isolates animals from contamination) (NRC 1996, pg. 119). Although conventional and barrier-space entry protocols for people, animals, and materials vary with the institution, for purposes of this report, a barrier will be defined as personnel fully gowned (gown, booties, gloves, face mask, and cap) and all material (racks, cages, feed, and bedding) autoclaved before entry into the barrier. Because animals housed in a barrier often have higher per diem costs to reflect their special treatment, underuse of a barrier facility or use of a barrier facility to house conventional animals can increase operating costs. Designing an animal facility with an expandable-contractible barrier can be cost-effective if a single-directional corridor system with multiple doors or air locks is used, beginning at sterile-equipment holding and terminating at soiled-cage washing. Alternative emergency exits must be available. By using this concept, the barrier can be sized from an individual room or suite up to the entire facility in selected increments.
INTERSTITIAL SPACE
Interstitial space is defined as an accessible zone that permits personnel movement above the ceiling of a facility and is typically used for maintenance or modification of HVAC equipment and utilities serving the space below. Animal facilities are mechanically complex and require constant maintenance. Easy access to terminal reheat coils, dampers,

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ventilation ducts, utilities, shutoff valves and such HVAC equipment as HEPA filters (if used), and supply and exhaust boxes is critical for the proper operation of an animal facility. Most animal facilities are serviced from within the facility through access panels or lay-in hung-ceiling assemblies that require a 14- to 16-ft floor-to-floor height. A partial interstitial or full interstitial space above an animal facility is desirable and sometimes essential to maintain a barrier or containment facility, eliminate the need for access panels or lay-in hung ceilings, restrict personnel access, reduce noise, and perform routine or emergency maintenance. Proper design of interstitial space carefully coordinates the placement of all ventilation ducts and utilities while maintaining unobstructed service aisles. Partial interstitial space provides a walk surface above a part of the facility—typically over corridors—and requires a 16- to 18-ft floor-to-floor height. Full interstitial space provides a walk surface above the entire facility and requires an 18- to 20-ft floor-to-floor height. The increased cost of constructing an interstitial space over that of conventional construction is related to the greater floor-to-floor height (deeper basement or more exterior wall, depending on the animal facility location), the walk surface, and the mechanical coordination needed to create service aisles. The exact increase in costs will vary from one project to another and should be estimated accordingly. On a recent two-level, 103,600-gross-square-foot animal research facility project, the cost of partial interstitial space was $705,000 (catwalk, $345,000; excavation and structure, $195,000; and mechanical, $165,000) and for full interstitial space, $2,665,000 (additional floor, $560,000; excavation and structure, $1,650,000; mechanical, $455,000). The increase in costs can be offset by a lower life-cycle cost achieved through ease of access for maintenance over the life of the facility, with some initial savings realized during construction because multiple trades can work simultaneously above and below the ceiling.
WALL MATERIALS AND FINISHES
Concrete masonry units (CMUs) have been used extensively in animal facility construction because of their durability and familiarity. The quality of CMU installations can vary considerably, depending on the surface quality of the block, the dimensional stability of the block, installation, filler application, primer, and final paint coats. Typically, wall guards are added to protect the painted finish as well. Other materials— such as water-resistant gypsum wall board (WRGWB), solid cement board (Titon-Board®), and fiberglass-reinforced panels (FRPs)—have been used successfully in rodent-based animal facilities. Titon-Board is a unique product consisting of solid cement board with a smooth face. The relative costs of these installed wall systems are as follows: CMU with epoxy paint, $19/ft2; Titon-Board with epoxy paint, $11/ft2; 4-mm FRPs, $25/ft2;

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6-mm FRPs, $27/ft2; and WRGWB, $9.50/ft2. The board-panel assemblies can be constructed quickly and result in a very smooth finish, compared with CMUs; with wall protection, they can hold up well against the demands of rodent-based animal facilities.
SUMMARY
In summary the major finding and opinions expressed in this chapter are as follows:
Proper design of the animal facility is a major determinant of the institution's ability to deliver cost-effective animal care. The design team should include the facility director, facility manager, researchers and representatives of the animal care staff with day-to-day experience in the facility.
Cost reductions should be calculated over the life the facility and take into account equipment, material and workforce interactions and durability.
Labor savings are a distinct advantage for the use of ventilated rack systems for mice due to the reduction in the frequency of cage changing. In addition, ventilated cage systems connected to the room exhaust have the advantage of improving room air quality and reducing worker exposure. Careful selection and analysis of available ventilated cage systems for the conditions of intended use are necessary for a sound financial decision and improved operational efficiency.
The use of conventional water delivery via bottle is laborious, time-consuming and likely to produce repetitive motion injuries in personnel. Automatic watering systems and alternative water bottle design and methods of handling warrant evaluation as a possible cost-saving, injury-sparing measure.
Designers of animal rooms should take into consideration ease of equipment use and animal handling to reduce worker fatigue and injury.
The use of robotic equipment to perform monotonous tasks, such as preparing cages for washing, is projected to have financial advantages and to reduce the incidence of ergonomic injuries in personnel. Robotic equipment may prove to be a viable investment for institutions processing as few as 2,000-2,500 cages daily.
Interstitial space for access to the animal facility mechanical areas should be provided because these areas require frequent preventive maintenance and repair services that are disruptive to ongoing research and smooth facility operations.
Wall materials that are durable but less expensive than the widely used concrete masonry units may be appropriate in some animal facility applications.

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